Ferrous alloys and abrasive-resistant articles made therefrom



Patented Nov. 13, 1951 UNITED STATES PATENT OFFICE FERROUS ALLOYS ANDABRASIVE-RE SI ST- ANT ARTICLES MADE THEREFROM David J. Giles, Latrobe,Pa., assignor to Latrobe Electric Steel Company, Latrobe, Pa., acorporation. of Pennsylvania No Drawing. Application January 10, 1951,,Serial No. 205,441

Claims.

for steels having a materially greater resistance to abrasion than thosecommercially available and at the same time being easy to form, easy togrind and having good impact strength, i. e., ability to withstandshock. A good example is steel for use in the fabrication of router andshaper' bits and lathe tools for the woodworking industry, and for otherarticles which are subject to considerable abrasion and shock and arethereby rapidly worn to a point where they can nol'onger meet requiredtolerances in the industry and must be resharpened, resurfaced orotherwise broughtback to the tolerances of the industry.

' In alloys for use in installations such as are described above inwhich the metal is subject to continual or recurring abrasion andimpact, it isdesirable that they be forgeable and hardenableand yetresist the action of abrasive subtances and the shock of intermittentimpacts. Historically, the search for alloys having certain desirableproperties has lead to various combinations of alloying elementsincluding combinations with vanadium. I have found, however, that whilethe general trend in vanadium alloys of steel has been in the directionof greater hardenability this is not alone the answer to the problem ofabrasion resistance, and this is especially true when resistance toshock is also required.

I have discovered certain alloys having satisfactory forgeability andhardenability which can be made abrasive-resistant by properlycontrolling the carbon and vanadium content in a man-- ner described inmy copending application Serial No. 118,448, filed September 28} 1949,now abandoned, of which this is a continuation-in-part, withoutmaterially altering their forgeability and hardenability. One of thesealloys is the subject of United States patent application Serial No.91,002, filed May 2, 1949, now abandoned.

My present invention provides an abrasionre'sisting alloy in whichcarbon, within certain limits, is added in excess of that necessary togive the alloy the desired forging and hardening characteristics andvanadium is added in an amount, again within certain limits, such thatthe ratio of the vanadium in excess of about 1% to the aforementionedexcess of carbon is about 4.2:1.

Considering only the essential elements of my alloy, the preferredanalysis for most combined abrasion and shock resisting applications is:

Per cent Mo 1.1 Balance substantially iron with residual impurities' inordinary amounts;

The composition. of my alloy may, however,

extend over a wider range and still retain its desirable abrasiveresistance- It may include. alloying elements such as nickel, tungstenandcobalt in restricted amounts without detrimentally affecting theability of the alloy to resist abrasion. The composition may fall withinthe limits. of. the following range of concentrations of alloyingelements.

Si 1% maximum Mn 1.5% maximum Cr we--- 4%-8% Mo Less than 1.5% W -l Lessthan 3% Co Less than 5% Ni Less than 3% Balance substantially iron withresidual impurities in ordinary amounts.

Per cent C a.'." Cr 4-6 0.1-0.7 0.2-0.9 0.8-1.3 Balance substantiallyiron with residual impurities in ordinary amounts.

While. I have given specific silicon and manganese ranges in thecomposition of my a1loy,.

these concentrations are the concentrations which normally result fromthe raw materials which I have used and may accordingly vary withinreasonable limits depending upon the raw materials used.

By the expression less than followed by a percentage figure in thisapplication when referring to molybdenum, nickel, tungsten and cobalt, Imean that the particular element may be present in an amount not toexceed the percentage concentration given. The presence of theseelements is optional up to the amount specified in the ranges ofcomposition given above.

The alloy is foreable and is air hardening as well as beingabrasive-resistant when molybdenum is included in the composition. If itis .desired to produce an alloy having similar abrasion resistance andforgeability but at a reduced cost and for use where air hardening isnot necessary, the molybdenum may be omitted without materiallyaffecting the other desirable properties.

In order to illustrate the abrasive resistance of my new alloy severalheats were made within the range of composition specified above for mynew alloy. The abrasion resistance of the alloy of my present inventionand of an alloy steel having similar forgeability and hardenabilitycharacteristics previously used in applications for which my new alloyis intended were compared with the abrasion resistance of an 18-4-1highspeed steel taken as a standard of 100% abrasion.

Careful comparison of the composition of the test pieces and theirresistance to abrasion shows the superiority of the alloy of myinvention over the alloys now used for applications requiring abrasionresistance as well as its superiority over standard 18-41 high-speedsteel. The alloy previously used has lost about nine times as muchmaterial as the preferred alloy (alloy C) of my invention while thehigh-speed steel standard shows more than four times as much loss ofmaterial as does my preferred alloy.

The economic importance of these results becomes more apparent when itis realized that not only has the alloy of my present invention lostless than as much material as the 184-1 high-speed steel but it does notincorporate the costly percentage of alloying elements which appear inthe high-speed steel. Moreover, the alloy of this invention is easier toform, easier to grind, and is able to withstand shock better than thealloys having a higher chromium content as exemplified by the alloydescribed in my applica-- tion Serial No. 91,002 mentioned above.Thisnew alloy therefore serves a new field of usefulness in whichresistance to shock or impact isnecessary or desirable along withresistance to abrasion.

Peculiarly, the addition of excess carbon and vanadium in excess of 1%in the ratio of 4.2% vanadium to 1% carbon although increasing theabrasion resistance to a remarkable extent has little or no effect onthe forgeability or hardenability of my alloy over those same physicalprop-- erties of an alloy without such excess carbon and Table!vanadium. For example, the Rockwell C hard- Per cent abrasion 1 ness ofalloy C and alloy B are substantially idem-- Alloy A (standard) 100ties}, as are their forging properties. Their abra- Alloy B 207 siveresistances, however, are sharply distin- Alloy C 23 guished asillustrated in Table I. If, how v a 1 Per cent removed by abrasion, u)marked departure from this ratio of 4.2:1 is made,

Table II Alloy 0 Cr w v Mo Si Mn A .74 4.10 18.00 1.10 .30 .25 .25BalancesubstentiallyFe. B 1.02 5. 25 .25 1.10 0.30 0. 70 Do. 0 1.80 5.21 3.05 1.12 0.38 0. 70 n0.

Abrasion tests were also made on modifications of alloy C within thebroad limits of composition heretofore stated. The results of theseabrasion tests and the composition of the test pieces are given inTables III and IV below.

1 Per cent removed by abrasion as compared with alloy A.

then a marked change in forgeabilty and harden-' ability occurs, thedirection and extent of which depends upon the nature and extent ofparture from this ratio.

My researches indicate that when carbon and vanadium appear in the abovedescribed excess and ratio they modify the characteristics of the alloyby very desirably augmenting its abrasiveresistance without masking ornullifying the other physical characteristics of the basic alloy. I be-1 lieve that the extraordinary abrasive resistance of my alloy dependsupon the formation of vana dium carbides which remain out of solutionand accordingly do not afiect the hardenability or forgeability of myalloy. While this theory seems to be consistent with observable facts, Ido not- Table IV Alloy C Si Mn Or V M0 N1 W 00 l. 83 42 66 5. 45 4. 08l. 22 2. 71 Balance subst nti ll 1. 91 38 57 5. 22 4. 38 1. l9 2. 48 D0.3 a y Fe 1. 87 57 5. 92 3. 1. 31 4. 58 D0. 3. 55 47 58 5. 10 ll. 92D0. 1. 84- 59 66 7. 40 4. 22 DO. 4. 15 63 73 7. 40 12. 76 L32 3. 02 D0.

the dey bind-myself thereto. Thetiactiis that, whatever the I'mec'hanismmay he, the addition of carbon vanadiumintheiaboveldes'cribedfproportions vanadium, and the balancesubstantially iron with residual impurities 1 in o'rdinary'am'ounts,::in which ialloy the vanadium in excess of ab'out 1 iscombinedwith carbon in a ratio of 'about:.42:1.

2. 'iln-abrasion-resi'sting'alloycomprising about 1.65% to 1.95% ofcarbon, about-4% ta-6% f chromium, about 0.1% to 0.7% of 'silic'on,about 0.2% to 0.9% of manganese, about 0.8% to 1.3%

of molybdenum, about-3% to of vanadium, and the balance substantiallyiron with residual impurities inordinary amounts, in which alloy thevanadium in excess of about 1% is combined with carbon in a ratio'ofabout 4.2: 1.

An abrasion-resisting alloyccomprisin'g about 1.8% of carbon, about 5%of chromium, about 0.3% of silicon,ab,out 0.7% of manganese, about 4% ofvanadium, and the balance substantially iron with residual impurities inordinary amounts, in which alloy the-vanadium in excess dfabout 1% "iscombined withcarbon in *aratio of about 42:1.

4. An abrasion-resisting alloy comprising about 1.8% of carbon, 5% ofchromium, about 0.3% of silicon, about 0.7% of manganese, about 1.1% ofmolybdenum, about 4% of vanadium, and the balance substantially ironwith residual impurities in ordinary amounts, in which alloy thevanadium in excess of about 1 is combined with carbon in a ratio ofabout 4.2: 1.

5. An abrasion-resisting alloy having carbon in excess of that necessaryto give it the desired hardenability characteristics comprising about1.65% to 1.95% of carbon, about 4% to 6% of chromium, about 0.1% to 0.7%of silicon, about 0.2% to 0.9% of manganese, about 3% to 5% of vanadium,and the balance substantially iron with residual impurities in ordinaryamounts, and in which the concentrations of vanadium and carbon withinthe given limits are adjusted so that the ratio of vanadium in excess ofabout 1% to the excess carbon is about 4.2: 1.

6. An abrasion-resisting alloy having carbon in excess of that necessaryto give it the desired hardenability characteristics comprising about1.65% to 1.95% of carbon, about 4% to 6% of chromium, about 0.1% to 0.7%of silicon, about 0.2% to 0.9% of manganese, about 0.8% to 1.3% ofmolybdenum, about 3% to 5% of vanadium, and the balance substantiallyiron with residual impurities in ordinary amounts, and in which theconcentrations of vanadium and carbon within the given limits areadjusted so that the ratio of vanadium in excess of about 1% to theexcess carbon is about 4.2 1.

7. An abrasion-resisting alloy having carbon in excess of that necessaryto give it the desired hardenability characteristics comprising about1.8% of carbon, about 0.3% of silicon, about 0.7% of manganese, about 5%of chromium, about 1:70 of vanadium, and the balance substantially withtesiduarimpurities. inordinary amounts,

in which the concentrations of vanadium "and carbon within :the given.limits are :adjusted -:so that :the #ratio :of vanadium in excess cor"about 1% to the excess carbon is about 4.211.

B.=-An abrasionesisting alloy having carbon in excess of that-necessaryto give it the desired hardenability characteristics comprising rabout'1.85% 10fcarbomabout 0.3% :ofxsilicon, about 0.7

of manganesegabout 1.1 of molybdenum, about 5% of chromium, about 4% ofvanadium, and the balance substantially iron with residual impuritiesiii-ordinary amounts, in which the concentrations of vanadium and carbonWithin the given "limits are adjusted-so that the ratio of vanadium inexc'essof about 1% to the excess carbon is mi about 4.2 1.

9. abrasion-resisting article formed 'from a forgeable-abrasion-resisting steel comprising about 1'.65% to 1.95% cf carbon,about 4% to 6 .df-chr'oxniumabout 0.1% to 0.7% of silicon, about 0. 2'to 0.9% ofmanganese, about 3% to 5 of-vana'diumand the'balancesubstantially iron "with residual impurities in ordinary amounts,in'which' alloys the vanadium lHGXCGSS dfjabout 1 %=is combinedwithcarbon ina ratio of about "42251, said article :being characterized by a"factor iof hardenability and forgeability comparable-to a steelhavingless than 1% vanadium and a carbon content less than said -article by a'value equal to about 'thepercent vanadiumrin said article 1% 10.abmsion-resisting article formed from a forgeable abrasion-resistingsteel comprising about 1.65% to 1.95% of carbon, about 4% to 6% ofchromium, about 0.1% to 0.7% of silicon, about 0.2% to 0.9% ofmanganese, about 0.8% to 1.3 of molybdenum, about 3% to 5% of vanadium,and the balance substantially iron with residual impurities in ordinaryamounts, in which alloys the vanadium in excess of about 1% is combinedwith carbon in a ratio of about 4.2:1, said article being characterizedby a factor of hardenability and forgeability comparable to a steelhaving less than 1% vanadium and a carbon content less than said articleby a value equal to about the per cent vanadium in said article- 1% 4.2

11. Anabraslon-resisting article formed from a forgeableabrasion-resisting steel comprising about 1.8% of carbon, about 5% ofchromium about 0.3% of silicon, about 0.7% of manganese, about 1.1% ofmolybdenum, about 4% 01 vanadium, the balance substantially iron withresidual impurities in ordinary amounts in which alloy the vanadium inexcess of about 1% is combined with carbon in a ratio of about 4.2:1,said article being characterized by factors of hardenability andforgeability comparable to a steel having less than 1% vanadium and acarbon content less than said article by a value equal to about the percent vanadium in said article- 1 4.2

12. An article formed of forgeable abrasionresisting steel having carbonin excess of that necessary to give it the desired hardenabilitycharacteristics comprising about 1.65% to 1.95% of carbon, about 4% to6% of chromium, about 0.1% to 0.7% of silicon, about 0.2% to 0.9% ofmanganese, about 0.8% to 1.3% of molybdenum,

the per cent vanadium in said artic1e1% 4.2

13. An abrasion-resisting alloy comprising I about 1.4% to 4% of carbon,about 4% lie-8% chromium, about 3% to 13% vanadium, about 1% maximumsilicon, about 1.5% maximum manganese, less than about 1.5% molybdenum;less than about 3% nickel, less than about 3% tungsten, less than about5% cobalt and the balance substantially iron with residual impurities inordinary amounts, in which alloy the vanadium in excess of about 1% iscombined with carbon in a ratio of about 42:1.

14. An abrasion-resisting alloy having carbon in excess of thatnecessary to give it-the desired hardenability characteristicscomprising about 1.4% to 4% of carbon, about 4% to 8% chromium, about 3%to 13% vanadium, about 1% maximum silicon, about 1.5% maximum manganese,,less than about 1.5 molybdenum, less than about 3 tungsten, less thanabout 5% cobalt and the balance substantially iron with residualimpurities in ordinary amounts, and in which the concentrations ofvanadium and carbon-are adjusted so that the ratio of vanadium in excessof about 1% to the excess carbon is about 4.211. 15. Anabrasion-resisting article formed of abrasion resisting steel havingcarbon. in excess of'that necessary to give it the desired hardenabilitycharacteristics comprising about 1.4% to 4% carbon, about 4% to 8%chromium, about 3% to 13% vanadium, about 1% maximum silicon; about 1.5%maximum manganese, less than about 1.5% molybdenum, less than about 3%tungsten, less than about 5% cobalt and the balance substantially ironwith residual impurities in ordinary amounts, and in which theconcentrations of vanadium and carbon within the given limits areadjusted so that the ratio of vanadium in excess of about 1% to theexcess carbon is about 412:1, said article being characterized by highresistance to abrasion and by forging and hardening characteristicscomparable to steels having a carbon content less than that of thearticle by an amount equal to the the per cent vanadiurn l 4.2

DAVID J. GILES. H

REFERENCES CITED I FOREIGN PATENTS Number Country Date 832,703 FranceOct. 3, 1938. 834,198 France Nov. 15, 1938

1. AN ABRASION-RESISTING ALLOY COMPRISING ABOUT 1.65% TO 1.95% OFCARBON, ABOUT 4% TO 6% OF CHROMIUM, ABOUT 0.1% TO 0.7% OF SILICON, ABOUT0.2% TO 0.9% OF MANGANESE, ABOUT 3% TO 5% OF VANADIUM, AND THE BALANCESUBSTANTIALLY IRON WITH RESIDUAL IMPURITIES IN ORDINAKRY AMOUNTS, INWHICH ALLOY THE VANADIUM IN EXCESS OF ABOUT 1% IS COMBINED WITH CARBONIN A RATIO OF ABOUT 4.2:1.